Domestic oven with smoke leakage prevention



July 18, 1967 G. A. scoTT f 3,331,942

v DOMESTIC OVEN WITH SMOKE LEAKAGE PREVENTION Filed March 2, 1965 2 Sheets-Sheet 2 INVENTOR. GEORGE A. SCOTT HIS ATTORNEY United States Patent O 3,331,942 DUMESTIC OVEN WITH SMKE LEAKAGE PREVENTIN George A. Scott, Jeifersontown, Ky., assigner to General Electric Company, a corporation of New York Filed' Mar. 2, 1965, Ser. No. 436,615 4 Claims. (Cl. 219-391) ABSTRACT OF THE DISCLOSURE A domestic 'oven having an air cooling chamber surrounding the walls forming the oven cavity. An air circulating means is provided for drawing room air through the cooling chamber. This cooling air tends to draw smoke from the oven cavity through oven component mounting openings in the said walls during an oven heating cycle. This smoke leakage is prevented by a shroud that encircles the oven components either individually or as a group and blocks the cooling chamber to isolate the components from the negative pressure area induced by the air circulating means.

The present invention relates to domestic baking ovens and particularly to -a high temperature oven that is provided with an air cooling means outside of the oven cavity for removing some of the heat in the walls of the oven liner so as to restrict the maximum external temperatures of the oven cabinet.

This invention was conceived during the development of a built-in wall oven design that incorporates a high temperature self-cleaning oven cycle using the principle of pyrolysis for removing the food soil and grease spatter from the surfaces of the oven liner. The basic principles of a self-cleaning oven are described and claimed in the recent patent of Bohdan Hurko, No. 3,121,158, which is assigned to General Electric Company, assignee of the present invention. Such a self-cleaning oven cycle has a maximum oven temperature between about 750 F. and about 950 F. so as to decompose all food soil and grease `spattter lodged on the oven liner walls by degrading the soil into gaseous products which are passed through an oxidation unit or smoke eliminator which further decomposes the gases ybefore returning the exhaust gases to the kitchen atmosphere.

A special temperature problem exists when such high temperatures are used in a built-in wall oven since the oven is totally enclosed except for the front portion thereof. Means must be provided to restrict the maximum operating temperatures of the outer surfaces of the oven cabinet as well as to keep the control components as cool as possible in order to extend the useful life thereof. In a free-standing range the control components can be located in areas remote from the oven heat, but in the compact design of a built-in wall oven a forced air cooling system is believed to be imperative. It is also important to prevent the air cooling system from drawing smoke out of the oven cavity around the oven components that are mounted through the walls of the oven liner.

The particular air cooling system for the domestic oven of the present invention is best described and claimed in the copending application of George A. Scott and J. Kirk Newell, Jr., Ser. No. 436,436, now Patent No. 3,310,046, which was filed concurrently herewith, and entitled Domestic Oven With Air Cooling System. It is also assigned to the General Electric Company, the ass-ignee of the present invention.

The principal object of the present invention is to provide a domestic oven with an air cooling system around the outside of the oven liner with means for preventing the leakage of smoke into the cooling system.

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A further object of the present invention is to provide, in the external air cooling system of a high temperature oven, a shroud means to isolate the possible avenues of smoke leakage from the cooling system.

A still further object of the present invention is to provide a high temperature oven with an external air cooling system where a negative pressure area in the cooling system is isolated from any air leakage paths from the oven cavity.

The present invention, in accordance with one form thereof, is embodied in a domestic oven having inner walls defining an oven cooking cavity where the Walls are surrounded 'by an oven cabinet that is spaced therefrom to form a cooling air chamber. An air circulation means is combined with the air chamber for creating a draft of relatively cool room air to remove some of the heat present in the oven liner walls. Certain oven components are mounted through one wall of the oven liner, and a partition or isolation means serves to close the air chamber in this vicinity and prevent the reduced air pressure area of the air circulation means from drawing smoke from out of the oven cavity.

My invention will be better understood from the following description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.

FIGURE 1 is a right side elevational view of an electric Ioven for use as a built-in wall oven with parts broken away and some in cross-section to show the means for removing some of the heat from the oven liner walls, as well as the means for preventing smoke leakage into the cooling system;

FIGURE 2 is a fragmentary cross-sectional plan view at the back of the oven taken on the lines 2-2 of FIGURE 1 to show the isolation means to prevent smoke leakage from the oven cavity into the cooling air circulation system; and

FIGURE 3 is a rear elevational view of the oven of FIGURE l with parts broken away along the left side of the oven to show the air space between the insulation guard and outer oven cabinet as well as the nature of the oven components mounted through the back wall of the oven liner.

Turning now to a consideration of the drawings, and in praticular to FIGURE l, there is shown a right side elevational view of a built-in wall oven 10 having an oven cavity 11 formed by a box-like oven liner 12 with a front opening that is adapted to be closed by an oven door 13. This particular oven in an electric oven having a lower baking element 14 and an upper broiling element 15, as is conventional in this art. An additional heating means is used in the form of ya perimeter or mullion heater 17 adjacent the front of the oven and encircling the oven liner so as to compensate for heat loss through and around the oven door as well as for obtaining generally uniform temperature throughout the oven cavity during the high temperature heat cleaning cycle, as was mentioned heretofore.

Due to the high temperatures utilized in this oven, an extra amount of thermal insulation 19, such as berglass or the like, is assembled around the outside of the oven liner 12 for retaining as much of the oven heat as is possible within the open cavity. In a similar manner, the oven door 13 is heavily insulated as compared with a standard oven door. A special high temperature door gasket 21 is adapted to be compressed against the front peripheral edge of the oven liner 12 for sealing the oven cavity when the -door is closed as well as restricting the amount of air that enters the cavity during the heat-cleaning cycle so as to control the rate of decomposition of the food soil. Moreover, there is an oven door latching mechanism 22 diagrammatically shown as only a latch handle for locking the oven door 13 in the closed position and preventing the unlocking thereof while the oven temperature is labove a predetermined maximum cooking temperature. Su-ch a door latching mechanism does not form part of the present invention, therefore, it is neither shown nor described in detail as many different types of door latching mechanisms m-ay be used without departing from the scope of the present invention.

In order to support the fibrous oven insulation 19 in its proper place an insulation guard 24 of thin sheet metal, as seen in FIGURE 2, surrounds the insulation especially adjacent the bottom of the oven and along t-he vertical walls, that is, the two side walls and the back wall. This support means is not as necessary at the top wall because of the force of gravity. Hence, it will be noted in FIG- URE 1 toward the back of the oven that the insulation 19 over the top of the oven liner is not covered by a sheet metal panel or insulation guard. Also, it will lbe understood by those skilled in this art that in actual practice the insulation guard 24 is a box-like structure into which the insulation 19 is assembled prior to the insertion of the oven liner 12 through the front wall of the 4outer cabinet of the oven. An outer oven cabinet structure 26 sur-rounds the insulation guard and is spaced outwardly therefrom to provide an :air space 27 that completely surrounds the insulated oven liner as is best seen in FIGURES 1 and 2. Also, in actual practice it is easier to assemble these various oven elements from the outside in rather than from the inside out as has been described above.

At the front of the oven beneath the oven door 13 is an open grill work 29 of elongated shape that extends from side to side thereof and serves as a primary air inlet means for the air space 27. Additional air inlet openings 30 are formed in the outer oven cabinet 26 at the two sides of the oven door opening adjacent the top thereof, as is best seen in lFIGURES l and 3. A control panel 32 is positioned above the oven door 13 and it contains the various electrical controls indicated broadly as element 33 and including such devices as an oven selector switch, an oven thermostat, a clock-timer, meat thermometer indicator and perhaps a convenience outlet. Such devices are not shown but they are readily recognizable by those skilled in this art. Beneath the control panel 32 is shown the beforementioned handle 22 for operating the door latching mechanism. The handle extends through a suitable elongated slot in an open `grill work 34 which serves as an air outlet means for the air space 27. Behind the grill '34 is -a second grill 35 which serves to obstruct vision into the air space 27 behind the control panel 32. Moreover, a blower means 36, in the form of a motor driven fan 37, is mounted in the air space 27 at the top of the oven for directing air toward the control components 33 positioned 'behind the control panel 32 so as to draw relatively cool room air into the air space 27 through the air inlet openings 29` and 30 and carry the air generally towards the back of the oven and up the back and sides and then across the top and out through the air outlet opening 34 beneath the control panel 32.

The oven 1t? is also supplied with a catalytic oxidation unit 39 mounted over an opening in the top wall of the oven liner 12 and serving -as a venting means for the oven cavity 11 so that the hot gases emanating from the oven cavity pass through the oxidation unit Where they are further decomposed before vbeing returned to the kitchen through a horizontal duct work 40 having a nozzle 41. This oxidation unit 39 is of the general type described and claimed in the patent of Stanley B. Welch, No. 2,900,483, which is assigned to the General Electric Company, assignee of the present' invention, and it does not form part of the present invention.

As is standard practice in this art, several oven components are mounted through the lback wall of t-he oven liner 12 as is best seen in FIGURES 1 and 3. First there is the oven lamp 43 with its heat shielding lens 44 and external lampholder 45. Then, of course, there are the terminal ends 4'6, 47 and 48 of the bake element 14, broil element 15, and mullion heater 17, respectively. Usually small clearances are provided around these oven components in the back wall of the oven liner 12 as well as in the insulation guard 24 in order to allow for both expansion and contraction of the different materials having dissimilar coeiicients of thermal expansion. These clearances are also important for ease of assembly and the necessity for providing engineering tolerances to compensate for the we-aring down of the forming tools used in making the oven components as well as the oven liner and the insulation guard. Moreover, the bake element 14 is adapted to be hinged at its supported end at the back wall of t-he oven liner so that it may be tilted up slightly for ease of sweeping away a slight amount of ash that may form on the bottom lwall of the oven liner. This hinging action also requires oversized openings in the back wall for the extension of the bake unit terminals therethrough las will be understood by those skilled in the art.

When the walls of the oven liner .are heavily loaded with food soil and :grease spatter and the high temperature heat-cleaning cycle is initiated some smokin-g may take place in the oven cavity before the hot gases reach the oxidation unit 39. The unit 39 serves to further decompose the gases, soot, vapor, `and the like before the :gases are returned -to the kitchen atmosphere through the nozzle outlet 41. However, when the blower means 36 is energized to create a negative pressure in the air space upstream of the blower unit it may happen that smoke leaks through the clearance openings around the oven components in the back wall of the oven liner due to the pressure differential existing between the oven cavity and the air cooling system. Since the cooling air does not pass through the oxidation unit 39 this smoke may be discharged into the kitchen through the air outlet 34. This would be highly objectionable to the housewife .and means would have to be provided for preventing this possibility.

Lookin-g at the back portion of the oven in FIGURE 3, `a single four-sided shroud Sil encircles the several oven components 45-48 and extends rearwardly between the insulation guard 24 and the outer oven cabinet 26, as is best seen in FIGURE 2. This shroud 50 is in the form of a series of four Z-shaped angular members arranged in a rectangular coniiguration as elements SL54, as is seen in FIGURE 3. The back wall of the outer oven cabinet 26 is removable so as to permit access to the oven components 45-48 for assembly and wiring purposes. Thus, the space encompassed by the shroud 50 may be considered as a Wiring chamber S5 that is separate or isolated from the air space 27. Thus, when the blower means 36 is energized lthe forced vdraft through the air space 27 is not measurable in the wiring chamber 55. Admittedly, there are some slight clearance openings in the shroud 50 for ease of manufacture and assembly, but these openings are essentially closed by theV fact that venting openings in the form of a plurality of louvers 56 are formed in the back wall of the outer oven cabinet 26 in the area circumscribed by the shroud Si) so that the air pressure within the wiring chamber is at substantially atmospheric pressure rather than at a negative pressure as induced by the action ofthe blower means 36. These small clearance openings are considerably smaller than the effective area of the louvers. Some louvers are shown .at the bottom and some are at the top of the oven so as to obtain a slight chimney effect of room air passing through the wiring chamber, but in a sepa-rate closed circuit from the cooling -air that passes through the air space 27, as mentioned heretofore.

Having described above what is considered to be the preferred embodiment of the present invention, it will readily be apparent to those skilled in this art that the invention does not require a single shroud or partition means about all of the' leakage paths, but that individual isolating means may be employed for each potential leakage path as long as the negative pressure area of the air cooling system is isolated from the leakage path from the oven cavity. Also a forced draft blower means may be replaced by an loutside chimney connection to give a natural draft of cooling air.

Modifications of this invention will occur to those skilled in this art, therefore, it is to be understood that this invention is not limited to the particular embodiments disclosed but that it is intended to cover Iall modifications which are within the true spirit and scope of this invention as claimed.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A domestic oven comprising inner walls defining an oven cooking cavity, one wall having an access opening and a door for closing said opening, heating means in heat transfer relation with the `oven cavity for cooking foods placed therein, thermal insulating means surrounding the walls of the oven cavity, an outer oven cabinet surrounding the insulated oven Walls but outwardly spaced therefrom to form a cooling air chamber therebetween, the air chamber having an air inlet means and an air outlet means, draft inducing means within the oven cabinet for moving cooling lair through the air chamber, and a shroud in the air chamber for formin-g a wiring chamber adjacent the back of the oven that is closed to the air chamber, and vent openings in the exterior of the oven cabinet for communicating with the Wiring chamber, whereby the said draft inducing means creates a negative press-ure in the air chamber downstream of the draft inducing means, while the air pressure in the wiring chamber functions at about atmospheric pressure so there is substantially no air movement in the wiring chamber that is caused by the said draft inducing means. v

2. A domestic oven comprising oven liner walls forming an oven cavity Where one wall of the cavity includes a door for gaining access thereto, heating means in heat transfer relation with the oven cavity for cooking foods placed therein, thermal insulating means surrounding the oven liner, an outer oven cabinet surrounding the insulated oven liner and spaced outwardly therefrom to form a cooling air chamber therebetween, the air chamber including in series relationship an air inlet opening, a blower means and an air outlet opening for circulating ambient air over the oven liner walls, oven components having portions extending through the back wall of the insulated over liner, Ia shroud located between the back wall of the insulated oven liner and the oven cabinet and encircling at least some of the said oven components to form a wiring chamber that is closed to the air chamber and has a substantially -dead air space -that is not subject to the drawing power of the said blower means.

3. A domestic `oven comprising oven liner Walls forming an oven cavity where one wall of the cavity includes a door for gaining access thereto, heating means in heat transfer relation with the oven cavity for cooking foods placed therein, thermal insulating lmaterial covering the oven liner walls, -a first oven cabinet surrounding the insulated oven liner walls, and a second oven cabinet surrounding the first oven cabinet but spaced outwardly therefrom to form an air space there between, air inlet means and air outlet means communicating with the air space, blower means located within the air space for creating a forced draft of room ai-r through the air space, a first group of holes formed in one wall of the oven liner and communicating with a second group of holes in the first oven cabinet for mounting oven components therethrough, and means for sealing the oven cavity from the air space, said second group of holes being surrounded by said sealing means comprising a continuous frame which extends between the first and second cabinet structures and surrounds the said second group of holes thereby forming a partial obstruction in the air space as Well `as creating a smaller second air space, and vent openings in the second oven cabinet communicating with the said second air space within the said frame so that the blower means creates a negative pressure only in the said first Iair space but not in the said second air space.

4. A domestic oven comprising oven liner walls for-ming an oven cavity, where one wall of the cavity includes a door for gaining access thereto, heating means in heat transfer relation with the oven cavity for cooking foods placed therein, thermal insulating material covering the oven liner walls, an insulation guard surrounding the insulated oven liner Walls, and an outer oven cabinet surrounding the said insulation guard but spaced therefrom to forman air space therearound, and an air inlet and air outlet communicating with the air space, anda blower means within the air space so that relatively cool room air may circulate through the air space and dissipate some of the heat from the oven liner walls, oven components having portions extending through a back wall of the oven liner, and a single box-like shroud extending between the insulation guard and the outer oven cabinet and encircling at least some of the said component portions for isolating the said component portions from the air space.

References Cited UNITED STATES PATENTS 2,756,319 7/1956 Hatch 219-402 X 3,036,193 5/1962 Allen 219-408 X 3,121,158 2/1964 Hurko 219-397 3,211,892 10/ 1965 Swenson et al 219-411 RICHARD M. WOOD, Primary Examiner. C. L. ALBRI'ITON, Assistant Examiner. 

1. A DOMESTIC OVEN COMPRISING INNER WALLS DEFINING AN OVEN COOKING CAVITY, ONE WALL HAVING AN ACCESS OPENING AND A DOOR FOR CLOSING SAID OPENING, HEATING MEANS IN HEAT TRANSFER RELATION WITH THE OVEN CAVITY FOR COOKING FOODS PLACED THEREIN, THERMAL INSULATING MEANS SURROUNDING THE WALLS OF THE OVEN CAVITY, AN OUTER OVEN CABINET SURROUNDING THE INSULATED OVEN WALLS BUT OUTWARDLY SPACED THEREFROM TO FORM A COOLING AIR CHAMBER THEREBETWEEN, THE AIR CHAMBER HAVING AN AIR INLET MEANS AND AN AIR OUTLET MEANS, DRAFT INDUCING MEANS WITHIN THE OVEN CABINET FOR MOVING COOLING AIR THROUGH THE AIR CHAMBER, AND A SHROUD IN THE AIR CHAMBER FOR FORMING A WIRING CHAMBER ADJACENT THE BACK OF THE OVEN THAT IS CLOSED TO THE AIR CHAMBER, AND VENT OPENINGS IN THE EXTERIOR OF THE OVEN CABINET FOR COMMUNICATING WITH THE WIRING CHAMBER, WHEREBY THE SAID DRAFT INDUCING MEANS CREATES A NEGATIVE PRESSURE IN THE AIR CHAMBER DOWNSTREAM OF THE DRAFT INDUCING MEANS, WHILE THE AIR PRESSURE IN THE WIRING CHAMBER FUNCTIONS AT ABOUT ATMOSPHERIC PRESSURE SO THERE IS SUBSTANTIALLY NO AIR MOVEMENT IN THE WIRING CHAMBER THAT IS CAUSED BY THE SAID DRAFT INDUCING MEANS. 